From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 3516A2C for ; Sun, 9 Jun 2019 03:59:57 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from ozlabs.org (ozlabs.org [203.11.71.1]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 04F2276F for ; Sun, 9 Jun 2019 03:59:55 +0000 (UTC) Received: by ozlabs.org (Postfix, from userid 1011) id 45M2bF3Lpnz9sNk; Sun, 9 Jun 2019 13:59:53 +1000 (AEST) From: Rusty Russell To: Russell O'Connor , Bitcoin Protocol Discussion In-Reply-To: References: <871s0c1tvg.fsf@rustcorp.com.au> Date: Thu, 06 Jun 2019 12:38:50 +0930 Message-ID: <87r287o1fh.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Sun, 09 Jun 2019 08:18:41 +0000 Subject: Re: [bitcoin-dev] [PROPOSAL] Emergency RBF (BIP 125) X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Jun 2019 03:59:57 -0000 "Russell O'Connor" writes: > Hi Rusty, > > On Sun, Jun 2, 2019 at 9:21 AM Rusty Russell via bitcoin-dev < > bitcoin-dev@lists.linuxfoundation.org> wrote: > >> The new "emergency RBF" rule: >> >> 6. If the original transaction was not in the first 4,000,000 weight >> units of the fee-ordered mempool and the replacement transaction is, >> rules 3, 4 and 5 do not apply. >> >> This means: >> >> 3. This proposal does not open any significant new ability to RBF spam, >> since it can (usually) only be used once. IIUC bitcoind won't >> accept more that 100 descendents of an unconfirmed tx anyway. >> > > Is it not possible for Alice to grief Bob's node by alternating RBFing two > transactions, each one placing itself at the bottom of Bob's top 4,000,000 > weight mempool which pushes the other one below the top 4,000,000 weight, > and then repeating with the other transaction? It might be possible to > amend this proposal to partially mitigate this. Good point. This will cost Alice approximately one tx every block, but that may still be annoying. My intuition says it's hard to play these games across swathes of non-direct peers, since mempools are in constant flux and propagation is a bit random. What mitigations were you thinking? Cheers, Rusty.